Create a simple box.
Open the "Material Editor".
Choose an empty material slot. Rename it to your desired texture e.g. "textures/base_wall/metalfloor_wall_14".
Drag the material onto the box, and turn on "Show Map in Viewport".
Load a checker map into the Diffuse channel (this step is just for view purpose in 3dmax).
Note: You could also use a bitmap "textures/base_wall/metalfloor_wall_14".
Add a UVW map, change it to box mapping, and tiling 5x5.
Click File menu -> Export.
Choose ase format and save it into the models folder. (it won´t load otherwise in radiant if you try from somewhere else)
Use the settings in the screenshot.